Effect of process and purity index on fault occurrence

Abstract

Minor faults occur irregularly in an industrial process and, as an aid to their diagnosis, the following experiment was done. Batches of raw material were selected and each batch was divided into two equal sections: for each batch, one of the sections was processed by the standard method and the other by a slightly modified process, in which the temperature at one stage is reduced. Before processing, a purity index was measured for the whole batch of material. For the product from each section of material, it was recorded whether the minor faults did or did not occur. Results for 22 batches are given in Table H.1.